Nozzle

A nozzle of Frühneuhochdeutsch " Tüsel " for the mouth of a bellows tube is a tubular technical device. This may, at its entire length have the same area, expand, rejuvenate or have more complex shapes., By a nozzle

• Deflected a gas or liquid stream,
• Pressure into kinetic energy is transformed,
• A solid or viscous mass formed (see extruder ) or
• Distributed a liquid or gaseous substance evenly (see atomization )

Be.

Colloquially, it is called also the visible tail section of an aircraft turbine from a nozzle - and therefore of a jet plane.

Confusor / diffuser

A confusor (nozzle) is the counterpart of a diffuser. In a confusor tapers the tube cross section and thus the velocity of the fluid increases (liquid or gaseous), in contrast to the diffuser, which expands and in which the fluid flowing through is braked.

Example of use

A complex application example of a nozzle, the turbine engine in a supersonic aircraft. The air must flow around the internal components only in the subsonic range, since this would lead to a stall on the blades of the rotors and stators. The combustion chamber in this case would not have enough oxygen to be fed and turn out of the drive. To prevent this, on a diffuser in front of the engine. Before the exit of the air flow that has to be accelerated to a supersonic speed. This is done with the aid of the nozzle.

For engines with afterburner adjustable nozzles or convergent / divergent systems are used. In a nozzle provide not only the cross section and the flow rate but also the density and the kinetic pressure of the fluid medium a measure dar. These ratios are proportional interdependent values ​​. It follows that the cross-sectional area of the nozzle is supersonic zoom instead must decrease in order to achieve a higher flow rate.

The mathematical relationship can be explained (area - velocity relationship ) using the Rankine - Hugoniot equation:

• For subsonic flow ( subsonic flow velocity) a decrease in cross section causes an increase in speed. A subsonic nozzle is thus shaped convergent ( in the flow direction tapering ).
• For a supersonic or hypersonic flow (supersonic flow velocity) a cross-sectional increase causes an increase in speed. A corresponding hypersonic / supersonic nozzle is therefore divergent shape. The density is in a supersonic flow at a faster rate, as the flow rate increases.
• In a transonic flow is, because otherwise the equation has no solution, ie the narrowest cross section of the nozzle is the Mach number Ma = 1

The visible image on the nozzle of the rocket drive is " down from above" through flows and represents an example of a hypersonic and thus divergent nozzle